Structure prediction and antigenic site determination of CD4 antigen

Abstract

CD antigen are playing vital role in many diseases. The human CD4 molecule binds both human immunodeficiency virus (HIV) envelope protein gp120 and class II major histocompatibility complex (MHC) molecules. This binding help for the internalisation of HIV and its replication in host CD4 T-cells concentration fall drastically, a disastrous fall in CD4 T-cells destroy cell immediate defence and leaves the patients open to life threatening infection through opportunistic organism such as Pnemoastic carinii and cytomegalovirus. In the present investigation attempts have been made to study the structural and molecular aspects of CD4. To illustrate the stability of electrostatic representation, the solvent-accessible surface of the molecules was calculated using the Deepveiw or Swisspdb package. Two large positive and two large negative potential patches characterise the surface of the antigen in this system. One interesting feature of the CD4 interface is the high number of side chain residue. Energy minimisation analysis results showed the bond energy 550.838 KJ/mol, angle 1,176.970 KJ/mol, torsion 2,205.20 KJ/mol, non-bonded -9,726.67 KJ/mol, electrostatic-10,237.85 KJ/mol and improper 465.336 KJ/mol.